DESCRIPTION (Adapted from abstract): Dr. Hanna is committed to a career goal of pursuing research in clinical virology with an emphasis on understanding the mechanisms of drug resistance in HIV and on exploring therapeutic options for infection with resistant virus. His immediate goals are to consolidate his technical and theoretical knowledge of methods in molecular biology and virology and to gain further experience in developing scientifically sound approaches to clinically important questions in virology. 'Dr. D'Aquila, the mentor for the applicant, is a recognized authority on basic and clinical aspects of HIV drug resistance. The mentor's laboratory and institution include the equipment, technical expertise, and intellectual environment which is conducive to the development of the candidate into a productive independent investigator. The proposed research plan aims to study the genetic mechanisms of multidrug resistance in HIV reverse transcriptase (RT) and the consequences of resistance to one drug on the susceptibility to other drugs using virus isolated during virologic failure of various RT inhibitor combination-regimens. Methods include the use of bulk sequencing and clonal analysis to investigate the temporal relationship between majority and minority drug resistant quasispecies, use of phenotypic drug susceptibility assays to correlate genotypic resistance to drug susceptibility and cross-resistance patterns, construction of infectious clones to- confirm susceptibility results from selected clinical samples, and competition experiments to evaluate relative viral replicative fitness of different clones. A novel aspect of the research is to generate HIV resistant to multiple RT inhibitors through DNA shuffling and to evaluate the utility of this approach for rapid preclinical study of multidrug resistance. The breadth of research methods will provide the applicant with a comprehensive background in basic investigation in virology. a. Candidate: Dr. Hanna is an excellent candidate for a Mentored Clinical Scientist Development Award. He has a very good academic and clinical track record. b. Mentor: The mentor, Dr. Richard D'Aquilla has a strong history of research productivity and support, and is well qualified to mentor Dr. Hanna in the area of HIV viral resistance. c. Career Development Plan: The plan is focused and appropriate for this candidate. d. Research Plan: The application clearly describes the proposed experiments, the research should lead to the candidate's development as an independent investigator. There is some concern about the potential of missing specific isolates that are underrepresented early during drug therapy. e. Environment and Institutional Commitment: The research facilities and the learning environment at the Massachusetts General Hospital appear excellent. Institutional commitment to allocate necessary resources and protected time for Dr. Hanna to develop into an independent researcher is given by Dr. Bruce Walker, Director of the AIDS Research Center.